Choosing aluminium profiles

[Voicecoil]

Thanks for you answer. I checked the moment of inertia and there is indeed a big difference between the 45 series and the 40 series profiles. The 45 series is way more rigid. Since the rigidity of the base is the most important thing, maybe it is a good decision to spend a bit more on the better profiles?

Absolutely. As aluminium isn't as stiff as steel you need to get clever and use extrusions that make the best use of the material to get a rigid frame.